// Regex explanation:
// Starts with "S" and can contain more letters, can continue with space, then contains two numbers.
// Then starts with "E" again and can contain more letters, can continue with space, then contains two numbers.
var pattern = @"S\w?\s?(\d\d)\s?E\w?\s?(\d\d)";
var regex = new Regex(pattern, RegexOptions.IgnoreCase);
var match = regex.Match(fileName);